THE KINGDOM OF THE HELMET 79 



senses are always being deceived, and we have constantly 

 to relearn the aquatic commonplaces. 



I have dived hundreds of times on many scores of reefs, 

 yet here, I was certain, was an exception and I anchored 

 fore and aft directly above the center, intending to explore 

 it thoroughly, and confidently slid down the ladder. My 

 idea was to walk about, now and then to sit upon a coral 

 boulder, and to pursue my regular reef studies. 



My feet came to rest on the curved surface of a huge 

 brain coral seven fathoms down, and at the first glance 

 around I saw the utter falseness of the glimpse I had had 

 from the surface. It brought to mind the moon. When 

 this satellite is full it shows nothing to our telescope but a 

 smooth, flat, uninteresting surface, but when the shadow 

 of the earth falls obliquely athwart the craters, the three 

 dimensions of the mighty lunar cliffs and crags, volcanoes 

 and ranges leap to the eye. Similarly, from my glass- 

 bottomed boat the reef was flat with only rounded masses 

 of color. Now, on a level with my eye, the surface showed 

 itself as absolutely unwalkable. Using all four limbs I 

 made my way painfully a few yards from the ladder and 

 there found a cul-de-sac, bounded by a twenty-foot bot- 

 tomless crevasse, an overhanging cliff coated with slippery 

 sponges, a family group of diadema urchins with their 

 long, poisonous spines, and on the fourth side a sheer drop 

 into invisibility. Add to this that every square yard of 

 surface — coral or rock — had its diminutive, needle-sharp 

 crags and its concealed pot-holes; its half -hidden caverns 



